Add an 8272 results phase.

Components/8272/CommandDecoder.hpp

@@ -15,33 +15,33 @@
 
 namespace Intel::i8272 {
 
+enum class Command {
+	ReadData = 0x06,
+	ReadDeletedData = 0x0c,
+
+	WriteData = 0x05,
+	WriteDeletedData = 0x09,
+
+	ReadTrack = 0x02,
+	ReadID = 0x0a,
+	FormatTrack = 0x0d,
+
+	ScanLow = 0x11,
+	ScanLowOrEqual = 0x19,
+	ScanHighOrEqual = 0x1d,
+
+	Recalibrate = 0x07,
+	Seek = 0x0f,
+
+	SenseInterruptStatus = 0x08,
+	Specify = 0x03,
+	SenseDriveStatus = 0x04,
+
+	Invalid = 0x00,
+};
+
 class CommandDecoder {
 	public:
-		enum class Command {
-			ReadData = 0x06,
-			ReadDeletedData = 0x0c,
-
-			WriteData = 0x05,
-			WriteDeletedData = 0x09,
-
-			ReadTrack = 0x02,
-			ReadID = 0x0a,
-			FormatTrack = 0x0d,
-
-			ScanLow = 0x11,
-			ScanLowOrEqual = 0x19,
-			ScanHighOrEqual = 0x1d,
-
-			Recalibrate = 0x07,
-			Seek = 0x0f,
-
-			SenseInterruptStatus = 0x08,
-			Specify = 0x03,
-			SenseDriveStatus = 0x04,
-
-			Invalid = 0x00,
-		};
-
 		/// Add a byte to the current command.
 		void push_back(uint8_t byte) {
 			command_.push_back(byte);

Components/8272/Results.hpp

@@ -0,0 +1,65 @@
+//
+//  Results.hpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 27/11/2023.
+//  Copyright © 2023 Thomas Harte. All rights reserved.
+//
+
+#ifndef Results_hpp
+#define Results_hpp
+
+#include "CommandDecoder.hpp"
+#include "Status.hpp"
+
+namespace Intel::i8272 {
+
+class Results {
+	public:
+		/// Serialises the response to Command::Invalid and Command::SenseInterruptStatus when no interrupt source was found.
+		void serialise_none() {
+			result_ = { 0x80 };
+		}
+
+		/// Serialises the response to Command::SenseInterruptStatus for a found drive.
+		void serialise(const Status &status, uint8_t cylinder) {
+			result_ = { cylinder, status[0] };
+		}
+
+		/// Serialises the seven-byte response to Command::SenseDriveStatus.
+		void serialise(uint8_t flags, uint8_t drive_side) {
+			result_ = { uint8_t(flags | drive_side) };
+		}
+
+		/// Serialises the response to:
+		///
+		///	* Command::ReadData;
+		///	* Command::ReadDeletedData;
+		///	* Command::WriteData;
+		///	* Command::WriteDeletedData;
+		///	* Command::ReadID;
+		///	* Command::ReadTrack;
+		///	* Command::FormatTrack;
+		///	* Command::ScanLow; and
+		/// * Command::ScanHighOrEqual.
+		void serialise(const Status &status, uint8_t cylinder, uint8_t head, uint8_t sector, uint8_t size) {
+			result_ = { size, sector, head, cylinder, status[2], status[1], status[0] };
+		}
+
+		/// @returns @c true if all result bytes are exhausted; @c false otherwise.
+		bool empty() const 	{	return result_.empty();	}
+
+		/// @returns The next byte of the result.
+		uint8_t next() {
+			const uint8_t next = result_.back();
+			result_.pop_back();
+			return next;
+		}
+
+	private:
+		std::vector<uint8_t> result_;
+};
+
+}
+
+#endif /* Results_hpp */

Components/8272/Status.hpp

@@ -60,9 +60,8 @@ enum class Status3: uint8_t {
 	Fault				= 0x80,
 	WriteProtected 		= 0x40,
 	Ready				= 0x20,
-	Track9				= 0x10,
+	Track0				= 0x10,
 	TwoSided			= 0x08,
-
 	HeadAddress			= 0x04,
 	UnitSelect			= 0x03,
 };

Components/8272/i8272.cpp

@@ -268,7 +268,6 @@ void i8272::posit_event(int event_type) {
 			}
 
 			// Jump to the proper place.
-			using Command = CommandDecoder::Command;
 			switch(command_.command()) {
 				case Command::ReadData:
 				case Command::ReadDeletedData: